Breeds in central Asia in fairly narrow band from Sayan and Altai mountains of northern Mongolia and southern Siberia south-west through northern Sinkiang (western China), southern Kazakhstan, Kyrgyzstan, and Tajikistan to Himalayas. Overlaps with Yellow-browed Warbler to west and south-west of Lake Baykal, perhaps also in some places to south-east. Possibly isolated population of race mandellii in central China, mainly Szechwan, could extend further towards south-west than known at present.
Vagrant in France, Belgium, Netherlands, Germany, Denmark, Norway, Sweden, Finland, Poland, Austria, Italy, Turkey, Israel, Iraq; in Britain, c. 20 claimed but yet to be confirmed.

Breeds in montane and subalpine zones in middle latitudes of east Palearctic, generally at altitude of c. 2500-3500 m (recorded breeding at 4000 m), in open coniferous or mixed forest, at highest altitudes in birch, rhododendron, or krummholz zones, especially on sunny slopes, and also in bushes along mountain rivers. Winters in lower altitude broad-leaved woodland, gardens, and orchards.

Egg laying in May-June in Tien Shan and Altai, 4-7 eggs are laid, incubation 11-13 days.

Insects and A few other invertebrates.

This species has a large range, with an estimated global Extent of Occurrence of 1,000,000-10,000,000 km². The global population size has not been quantified, but it is believed to be large as the species is described as 'abundant' in at least parts of its range (Baker 1997). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.

Migratory; winters in Pakistan and Himalayan foothills east to Nepal (up to 2500 m), Sikkim, Bangladesh, northern Burma and Thailand, and widespread in Indian plains south to c. 16°N; in Delhi area, by far commonest Phylloscopus in winter apart from Chiffchaff. Also winters in southern Afghanistan, Iran, and a few in eastern Arabia. Leaves breeding grounds from August (mid-July at 3300 m in Kashmir), with main movement in western Siberia September to mid-October; reaches winter quarters from late September, and present in India mostly October-April. Northward movement begins late March, arriving in western Mongolia early May, and peak movement in western Siberia is 2nd half of May. Most vagrants to Europe and Levant recorded in late autumn (later than Yellow-browed Warbler) and overwintering regularly noted; commonly arrives together with vagrant Radde's Warbler, Dusky Warbler, and Pallas's Warbler.